Programming as problem solving

So far, we have used Java to print things out. We have used it for some calculations, but nothing we can't do on a calculator. Now, we will start learning concepts that will enable us to formulate problems as programming problems.

Programming as problem solving

What is an algorithm?

"An algorithm describes how a problem is solved by listing the actions that need to be taken and the order of their execution."

It is a set of instructions to help plan a program.

It is a recipe.

Variables

int week = 1;

double profit = 736.0;
                    

• Variables hold information and correspond to memory locations.
• The information they hold can change...usually
• Each variable has a:
  • type
  • size
  • name
  • value

Variables: type and size

Java variables can be of the following types and sizes:

Variables: names

• Use descriptive variable names. Long names are okay.
• Lowercase variable names, unless more than one word. Then, combine all words into one, and capitalize the first letter of each subsequent word. For example:
  • camelCasedVariableName

Variables: values

Once it is declared, the value of a variable can change...

int week;

week = 1;
week = 2;
                        

Variables: values

...unless it is a constant.

final int MAX_WEEKS = 5;
                        

Constants also have different naming conventions.

• Prefaced with final keyword.
• All caps.
• Underscores between words.

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